Gas analyzer with means for varying angle of incidence of light on interference filter

摘要

A gas analyzer provided with apertures on the optical paths from a light source through a cell to sensors and multi-layer interference band-pass filters on the respective optical paths. The structure makes it possible to change the distance between each sensor and the corresponding aperture, or the change the size of the aperture, for changing the maximum angle of incidence of light on the filters which is sensed by the sensors to thus change the central wavelength of the filters.